A122462 a(n) = gcd(b(n-1),b(n)), where b(i) = A122280(i).

2, 2, 3, 3, 3, 2, 5, 5, 3, 2, 2, 7, 7, 3, 2, 11, 11, 3, 3, 2, 2, 13, 13, 3, 2, 17, 17, 3, 2, 5, 5, 7, 2, 19, 19, 3, 5, 2, 23, 23, 3, 2, 2, 2, 2, 11, 5, 2, 29, 29, 3, 7, 7, 2, 31, 31, 3, 2, 13, 5, 2, 2, 37, 37, 3, 3, 3, 2, 2, 41, 41, 3, 3, 7, 11, 2, 43, 43, 3, 2, 2, 47, 47, 3, 2, 2, 5, 5, 5, 2, 2, 2

Offset: 3

Author

Klaus Brockhaus, Sep 09 2006

Keywords

• nonn

Comments

Primes arising in A122280 as greatest common divisor.

Crossrefs

Cf. A122280.

Programs

PARI

{m=100;z=2*m;w=vectorsmall(z);b=1;a=2;w[b]=1;w[a]=1;stop=0;n=3;while(!stop&&n<=m,j=1;while(j<=z&&(w[j]==1||!isprime(p=gcd(a,j))),j++);if(j>z,stop=1,print1(p,",");a=j;w[a]=1;n++))}